1. Field of the Invention
The present invention relates generally to form-fill-seal machines and, more particularly, to certain new and useful improvements in the manufacture of such machines in an unusually compact size capable of producing sealed cups and other sealed package structures with increased efficiency.
2. Description of the Prior Art
"Form-fill-seal" is the generic name for a type of machine in which a first thermoformable plastic web is indexed (in most cases, intermittently) to a heating station where the web is brought to forming temperature and then indexed to a forming station where the heated plastic web is drawn by vacuum or pressed by air pressure, or both, either over or into one or more forming dies to thereby form the web into the desired configuration, usually a cup-like cavity.
During the time of forming at the forming station, the web is normally clamped continuously about the periphery of each forming die. Also, the forming dies typically are retractably mounted so that, once the desired formation is made in the web, the die retracts and the formed web is then able to advance to a filling station, which delivers a discrete predetermined amount of product into each cup-like formation.
Simultaneous with the formation and filling of the aforesaid first web, a second web, usually in an upper position and printed, either in a continuous pattern, which requires no registration, or in a design which must be in accurate registration with the bottom web formation so that a complete single pattern or design will be located over each cup or other formation in the first web.
The second upper web, by means of various rollers, is brought into parallel proximity with the formed and filled lower web and then indexed simultaneously in printed register therewith, where necessary, to a sealing station. At the sealing station, retractable heated sealing dies clamp and seal the lower formed and filled web to the upper web and then withdraw to permit further indexing of the sealed packages to a final station where the individual packages are separated and delivered to a packing or loading station.
In general, previously known form-fill-seal machines for packages are large, unwieldy, and extremely expensive. For example, a widely used machine for producing plastic cups of butter, margarine and the like is approximately 25 ft. long and costs in the neighborhood of $400-$500 Thousand (U.S.), yet only produces on the order of 500 cups per minute of 5-gram size.